New findings show the Earth, and the moon, are about 60 million years older than previously believed.
Guillaume Avice and Bernard Marty, geochemists from the University of Lorraine in Nancy, France, discovered the cosmic birth certificate error. You can’t just do normal geology when you’re trying to study things that happened before that geology formed, so the team had to do a bit of scientific detective work.
One way to discover the age of things is to compare current ratios of gases to ratios in ancient materials. These “isotopic ratios” change over time in a way that can be used to determine how much time has passed. The pair had very, very old and well-preserved materials to work with, samples of roughly three-billion-year-old quartz with xenon sealed inside found in South Africa and Australia. They analyzed this “time capsule” and compared its isotopic ratios of xenon current ones.
This allowed them to make a better calculation of the moment when another planet-sized body slammed into the Earth, creating the Earth and moon we see today. They pegged it at 40 million years into the formation of the solar system, 60 million earlier than previously thought. Plus or minus twenty million years, because the exact date can’t really be pinned down.
“It is not possible to give an exact date for the formation of the Earth. What this work does is to show that the Earth is older than we thought, by around 60 million years,” Avice said .
The oldest rocks found in the solar system are 4,568 billion years old, so the earth is younger than that.
Marty said that although 60 million years might be a blip in cosmic time, it’s important to get the date right.
“This might seem a small difference, but it is important. These differences set time boundaries on how the planets evolved, especially through the major collisions in deep time which shaped the solar system,” he said.
[Source: Science Daily]
Image: Artist’s conception of a planetary collision from NASA